from sqlalchemy import (
    CheckConstraint, DateTime, Integer, ForeignKey, Index,
    String, UniqueConstraint, func,
)
from sqlalchemy.orm import Mapped, mapped_column, relationship
from datetime import datetime
from typing import Optional
from app.database import Base


class EventInvitation(Base):
    __tablename__ = "event_invitations"
    __table_args__ = (
        UniqueConstraint("event_id", "user_id", name="uq_event_invitations_event_user"),
        CheckConstraint(
            "status IN ('pending', 'accepted', 'tentative', 'declined')",
            name="ck_event_invitations_status",
        ),
        Index("ix_event_invitations_user_status", "user_id", "status"),
        Index("ix_event_invitations_event_id", "event_id"),
    )

    id: Mapped[int] = mapped_column(primary_key=True)
    event_id: Mapped[int] = mapped_column(
        Integer, ForeignKey("calendar_events.id", ondelete="CASCADE"), nullable=False
    )
    user_id: Mapped[int] = mapped_column(
        Integer, ForeignKey("users.id", ondelete="CASCADE"), nullable=False
    )
    invited_by: Mapped[Optional[int]] = mapped_column(
        Integer, ForeignKey("users.id", ondelete="SET NULL"), nullable=True
    )
    status: Mapped[str] = mapped_column(String(20), default="pending")
    invited_at: Mapped[datetime] = mapped_column(
        DateTime, default=func.now(), server_default=func.now()
    )
    responded_at: Mapped[Optional[datetime]] = mapped_column(DateTime, nullable=True)

    event: Mapped["CalendarEvent"] = relationship(lazy="raise")
    user: Mapped["User"] = relationship(foreign_keys=[user_id], lazy="raise")
    inviter: Mapped[Optional["User"]] = relationship(
        foreign_keys=[invited_by], lazy="raise"
    )
    overrides: Mapped[list["EventInvitationOverride"]] = relationship(
        lazy="raise", cascade="all, delete-orphan"
    )


class EventInvitationOverride(Base):
    __tablename__ = "event_invitation_overrides"
    __table_args__ = (
        UniqueConstraint("invitation_id", "occurrence_id", name="uq_invitation_override"),
        CheckConstraint(
            "status IN ('accepted', 'tentative', 'declined')",
            name="ck_invitation_override_status",
        ),
        Index("ix_invitation_overrides_lookup", "invitation_id", "occurrence_id"),
    )

    id: Mapped[int] = mapped_column(primary_key=True)
    invitation_id: Mapped[int] = mapped_column(
        Integer, ForeignKey("event_invitations.id", ondelete="CASCADE"), nullable=False
    )
    occurrence_id: Mapped[int] = mapped_column(
        Integer, ForeignKey("calendar_events.id", ondelete="CASCADE"), nullable=False
    )
    status: Mapped[str] = mapped_column(String(20), nullable=False)
    responded_at: Mapped[datetime] = mapped_column(
        DateTime, default=func.now(), server_default=func.now()
    )